1. Field
Exemplary embodiments of the invention relate to a method for recognizing whether a sample is introduced through measurement of a capacitance difference and a biosensor using the method.
2. Background
Recently, there has been increasing concern about biosensors that diagnose the state of a person tested through measurement of a biological sample.
Particularly, in diagnosing and preventing diabetes, the necessity of periodic monitoring of glucose concentrations in blood has been increased. Currently, each and every person can easily measure blood glucose using a strip type biosensor that is in the form of a hand-held portable measurement unit.
Recently commercialized biosensors measure blood glucose in a blood sample using the electrochemical principle, which is as follows.Glucose+GOx−FAD→gluconic acid+GOx−FADH2 GOx−FADH2+electron transfer mediator (oxidation state)→GOx−FAD+electron transfer mediator (reduction state)
In the above-described reaction formulas, GOx denotes glucose oxidase, and GOx−FAD and GOx−FADH2 denote an oxidation state and a reduction state of FAD (Flavin Adenine Dinucleotide) that is an active region of glucose oxidase, respectively.
The above-described measurements should be performed in a state where sufficient blood fills in an introduction channel in which working electrodes are provided. Otherwise, measurement error may occur. Accordingly, it is necessary to accurately grasp a time point when blood (sample) sufficiently fills in the introduction channel.
In the related art, a blood recognition electrode is exposedly arranged in a channel to which blood is introduced to primarily measure a signal that indicates whether the blood is introduced. That is, when a blood arrival signal is acquired, a voltage is primarily applied to acquire a current signal. However, the residual current signal that is caused by the primarily applied voltage may exert an influence on the measurement of the glucose concentrations when the glucose concentrations are measured by secondarily applying a measurement voltage to a working electrode and a reference electrode for actual measurement of the glucose concentrations at the next stage. Due to this, a fatal problem may occur on the accuracy and repeated implementation of the electrochemical biosensor.